I've been playing with the TCXO calibration of these boards. The vast majority of the correction factors are between -150PPB and -350PPB. I calibrated these boards earlier today when the wood stove was going and the boards were at 83F.
Now, the boards are 70°F and I am checking them again at 10MHz. I am seeing, on average, 30PPB difference. I have to subtract about 30PPB to bring them back to 10.000 000 0. The boards are about 0.2Hz to 0.3Hz higher at 70°F from when I calibrated them at 83°F.
The datasheet shows an operating temp range of -40°C to 85°C and a 0.5PPM across that range. That's 4PPB per °C if I interpret that correctly. 83°F - 70°F is 13°F, and that's a difference of 7.2°C. 7.2°C * 4PPB = 28.8 PPB. The temperature drift I am measuring seems to be spot on with the specs.
All this is to say, don't bother chasing that last tenth of a Hz if you calibrate.
Now, the boards are 70°F and I am checking them again at 10MHz. I am seeing, on average, 30PPB difference. I have to subtract about 30PPB to bring them back to 10.000 000 0. The boards are about 0.2Hz to 0.3Hz higher at 70°F from when I calibrated them at 83°F.
The datasheet shows an operating temp range of -40°C to 85°C and a 0.5PPM across that range. That's 4PPB per °C if I interpret that correctly. 83°F - 70°F is 13°F, and that's a difference of 7.2°C. 7.2°C * 4PPB = 28.8 PPB. The temperature drift I am measuring seems to be spot on with the specs.
All this is to say, don't bother chasing that last tenth of a Hz if you calibrate.